Sleeping in Japan can quite often be an expensive thing and unlike the USA where hotels charge per room, in Japan it is often a price per person. I am going to run through a couple different options that are decent, cheaper alternatives to regular hotels in Japan. See the other places to stay.
Another unique experience in Japan are the capsule hotels. Traditionally these hotels are made for business men who have missed the last train and just need a place to crash for the night. Basically you have enough space to lay down and that is it. Some people say it feels like you are sleeping in a coffin, so if you are claustrophobic, this is 100% not for you.